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Uppsala University

1. Valgeborg, Fredrik Stångberg. Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory.

Degree: Molecular and condensed matter physics, 2016, Uppsala University

Magnetism is a familiar phenomenon, and is applied in a variety of devices, from simple ones, like compasses, to the more sophisticated magnetic hard disk drives. It is also known that the magnetization of a material can change, for example by heating or by exposure to an external magnetic field. The dynamics of transitions between different magnetizations, however, is largely unknown, particularly in complex materials. To further the understanding of such dynamics, this thesis presents an observational study of the dynamics of laser induced demagnetization of permalloy (Ni0.8Fe0.2). Dynamics were studied with element-specificity, i.e. Fe and Ni were studied simultaneously, but separately, rather than studying the overall material. The study was conducted at the HELIOS laboratory at Uppsala University, which features equipment for the study of magnetization dynamics. Important concepts like high-order harmonic generation (HHG) and the transverse magneto-optic Kerr effect (T-MOKE) are discussed. HHG is the laser induced generation of high energy photons, and T-MOKE relates the intensity of reflected light to the magnetization of the reflecting material. The study revealed a very short demagnetization time, and maximum demagnetization of both elements was achieved within 1 picosecond. An onset delay in the demagnetizations of Fe and Ni of about 25 femtoseconds was also observed. Both phenomena have been previously reported. The results further imply that the magnetizations diverge over a 10 picosecond time interval after the onset of demagnetization, which has not been previously reported. The apparent divergence may be due to an unknown transient setup-related issue. The short demagnetization times, as well as the onset delay could potentially contribute to the development of a more complete theory of magnetization dynamics.

Magnetism är ett bekant fenomen, som utnyttjas i allt från enkla tillämpningar, som kompasser,till mer sofistikerade sådana, som hårddiskar. Det är också känt att magnetiseringen i ett material kan ändras, t.ex. genom upphettning eller genom att det utsätts för ett yttremagnetiskt fält. Dynamiken vid övergångar mellan olika magnetiseringstillstånd är dock ett relativt okänt ämne, i synnerhet när det kommer till komplexa material. För främjandet av en större förståelse inom ämnet, presenteras här en observationell studie av dynamiken för laserinducerad avmagnetisering av permalloy (Ni0.8Fe0.2). Dynamiken undersöktes med grundämnesspecificitet, d.v.s. Fe och Ni undersöktes samtidigt, men var för sig, snarare än att materialet undersöktes som helhet. Undersökningen gjordes vid HELIOS-laboratoriet vid Uppsala Universitet, som tillhandahåller utrustning för undersökning av magnetiseringsdynamik. Viktiga koncept diskuteras, såsom övertonsgenerering och den transversella magnetooptiska Kerr-effekten (T-MOKE). Övertonsgenerering innebär laserinducerad generering av högenergifotoner, och T-MOKE relaterar reflekterad intensitet till…

Subjects/Keywords: magnetization dynamics; magnetization; demagnetization; magnetism; element-specific; element-specificity; T-MOKE; MOKE; pump-prob; time-resolved pump-probe; HHG; high-order harmonic generation; overtone generation; HELIOS; magnetiseringsdynamik; magnetisering; avmagnetisering; magnetism; grundämnesspecifik; grundämnesspecificitet; T-MOKE; MOKE; pump-prob; tidsupplöst pump-prob; HHG; övertonsgenerering; HELIOS

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Valgeborg, F. S. (2016). Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory. (Thesis). Uppsala University. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297598

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Valgeborg, Fredrik Stångberg. “Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory.” 2016. Thesis, Uppsala University. Accessed May 09, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297598.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Valgeborg, Fredrik Stångberg. “Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory.” 2016. Web. 09 May 2021.

Vancouver:

Valgeborg FS. Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory. [Internet] [Thesis]. Uppsala University; 2016. [cited 2021 May 09]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297598.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Valgeborg FS. Element-Specific Magnetization Dynamics Using T-MOKE at the HELIOS Laboratory. [Thesis]. Uppsala University; 2016. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297598

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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